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[C++] PR c++/89576 - if constexpr of lambda capture.

Message ID 20190306183803.3942-1-jason@redhat.com
State New
Headers show
Series [C++] PR c++/89576 - if constexpr of lambda capture. | expand

Commit Message

Jason Merrill March 6, 2019, 6:38 p.m. UTC 
Now that we're doing implicit lambda capture in templates, we see x here as
the lambda capture.  maybe_convert_cond was doing nothing in a template, so
we never called mark_rvalue_use on x.  As part of the broad move toward
doing more processing of non-dependent expressions, let's do this
conversion.

Tested x86_64-pc-linux-gnu, applying to trunk.

	* semantics.c (maybe_convert_cond): Do convert a non-dependent
	condition in a template.
	* typeck.c (condition_conversion): Handle being called in a
	template.
---
 gcc/cp/semantics.c                          |  4 ++--
 gcc/cp/typeck.c                             |  9 ++++-----
 gcc/testsuite/g++.dg/cpp1z/constexpr-if15.C |  2 +-
 gcc/testsuite/g++.dg/cpp1z/constexpr-if28.C | 11 +++++++++++
 gcc/cp/ChangeLog                            |  8 ++++++++
 5 files changed, 26 insertions(+), 8 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if28.C


base-commit: ad0ce1a5e76e19a5222cb0a529a245d8a7991114
diff mbox series

Patch

diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index c03e4ef247c..2573b77f6d6 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -646,10 +646,10 @@  maybe_convert_cond (tree cond)
     return NULL_TREE;
 
   /* Wait until we instantiate templates before doing conversion.  */
-  if (processing_template_decl)
+  if (type_dependent_expression_p (cond))
     return cond;
 
-  if (warn_sequence_point)
+  if (warn_sequence_point && !processing_template_decl)
     verify_sequence_points (cond);
 
   /* Do the conversion.  */
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 1bf9ad88141..8367497b539 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -5867,18 +5867,17 @@  cp_truthvalue_conversion (tree expr)
     return c_common_truthvalue_conversion (input_location, expr);
 }
 
-/* Just like cp_truthvalue_conversion, but we want a CLEANUP_POINT_EXPR.  */
+/* Just like cp_truthvalue_conversion, but we want a CLEANUP_POINT_EXPR.  This
+   is a low-level function; most callers should use maybe_convert_cond.  */
 
 tree
 condition_conversion (tree expr)
 {
   tree t;
-  /* Anything that might happen in a template should go through
-     maybe_convert_cond.  */
-  gcc_assert (!processing_template_decl);
   t = perform_implicit_conversion_flags (boolean_type_node, expr,
 					 tf_warning_or_error, LOOKUP_NORMAL);
-  t = fold_build_cleanup_point_expr (boolean_type_node, t);
+  if (!processing_template_decl)
+    t = fold_build_cleanup_point_expr (boolean_type_node, t);
   return t;
 }
 
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if15.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if15.C
index 1dd8beab89c..49c7b7abb63 100644
--- a/gcc/testsuite/g++.dg/cpp1z/constexpr-if15.C
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if15.C
@@ -7,5 +7,5 @@  constexpr int foo (int) { return 2; }
 template <typename>
 void a()
 {
-  if constexpr(foo) { };
+  if constexpr(foo) { };	// { dg-error "overloaded" }
 }
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if28.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if28.C
new file mode 100644
index 00000000000..8bfde6c1bdb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if28.C
@@ -0,0 +1,11 @@ 
+// PR c++/89576
+// { dg-do compile { target c++17 } }
+
+template <class T>
+void foo()
+{
+    constexpr int x = 0;
+    [&] {
+        if constexpr (x) {}
+    };
+}
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index d2cb7fd1132..f889b253f5a 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@ 
+2019-03-06  Jason Merrill  <jason@redhat.com>
+
+	PR c++/89576 - if constexpr of lambda capture.
+	* semantics.c (maybe_convert_cond): Do convert a non-dependent
+	condition in a template.
+	* typeck.c (condition_conversion): Handle being called in a
+	template.
+
 2019-03-05  Jason Merrill  <jason@redhat.com>
 
 	* class.c (is_really_empty_class): Add ignore_vptr parm.